U.S. patent application number 16/108389 was filed with the patent office on 2019-02-28 for compound sensor.
The applicant listed for this patent is CANON KABUSHIKI KAISHA. Invention is credited to Atsushi Kandori.
Application Number | 20190064013 16/108389 |
Document ID | / |
Family ID | 65437413 |
Filed Date | 2019-02-28 |
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United States Patent
Application |
20190064013 |
Kind Code |
A1 |
Kandori; Atsushi |
February 28, 2019 |
COMPOUND SENSOR
Abstract
A compound sensor that is capable of being used with robotics is
provided such that the compound sensor includes a distance
measurement unit and a pressure measurement unit. Further, a
contact detection unit, which is dedicated to performing a
detection when a measurement target contacts with a surface of the
sensor is included.
Inventors: |
Kandori; Atsushi;
(Ebina-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CANON KABUSHIKI KAISHA |
Tokyo |
|
JP |
|
|
Family ID: |
65437413 |
Appl. No.: |
16/108389 |
Filed: |
August 22, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B25J 13/081 20130101;
G01L 9/08 20130101; G01L 1/162 20130101; B25J 13/086 20130101; G01L
11/06 20130101; G01L 1/146 20130101; G01L 9/0022 20130101; G01L
1/255 20130101; G01L 5/228 20130101; H01L 41/1132 20130101; B25J
19/026 20130101; B25J 13/084 20130101 |
International
Class: |
G01L 1/25 20060101
G01L001/25; G01L 11/06 20060101 G01L011/06; G01L 9/00 20060101
G01L009/00; G01L 9/08 20060101 G01L009/08; H01L 41/113 20060101
H01L041/113; G01L 1/16 20060101 G01L001/16; G01L 5/22 20060101
G01L005/22; B25J 13/08 20060101 B25J013/08; B25J 19/02 20060101
B25J019/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 25, 2017 |
JP |
2017-162617 |
Claims
1. A compound sensor comprising: a distance measurement unit
configured to measure a distance from a measurement target by
transmitting an ultrasonic wave and receiving the ultrasonic wave
returned from the measurement target; a pressure measurement unit
configured to measure a pressure applied from the measurement
target; and a contact detection unit configured to detect a
presence of a contact with the measurement target.
2. The compound sensor according to claim 1, wherein a vibrating
membrane having a piezoelectric film is included in one or more of
the distance measurement unit, the pressure measurement unit, or
the contact detection unit.
3. The compound sensor according to claim 1, wherein a vibrating
membrane having an electrode and another electrode that faces the
electrode is included in one or more of the distance measurement
unit, the pressure measurement unit, or the contact detection
unit.
4. The compound sensor according to claim 3, wherein one or more of
the distance measurement unit, the pressure measurement unit, or
the contact detection unit is a static capacitance type sensor.
5. The compound sensor according to claim 1, further comprising a
unit configured to switch between a distance measurement mode in
which only the distance measurement unit operates, a pressure
detection mode in which the pressure measurement unit operates, and
a contact detection mode in which all the distance measurement
unit, the pressure measurement unit, and the contact detection unit
operate.
6. The compound sensor according to claim 1, further comprising a
shear force detection unit.
7. The compound sensor according to claim 1, wherein on a first
substrate, a second substrate is provided via an elastic body, and
the distance measurement unit is provided on a face of the second
substrate, which is the face opposite to a face that faces to the
first substrate.
8. The compound sensor according to claim 7, wherein the second
substrate is provided movable by an external force.
9. The compound sensor according to claim 1, wherein the distance
measurement unit and the pressure measurement unit are provided as
a single unit.
10. The compound sensor according to claim 9, wherein based on a
detection signal from the contact detection unit, operation is
switched between distance measurement and pressure measurement.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention relates to a compound sensor including
a function as a proximity sensor for detecting a distance from a
nearby target by using an ultrasonic wave and a function as a
tactile sensor for detecting a contact pressure from the
target.
Description of the Related Art
[0002] When a robot hand tries to hold an object, a control is
executed based on image information captured by a camera or the
like. However, when the robot hand approaches to the object or
touches the object, the information obtained from the image
information from the camera is limited. Thus, to compensate the
lack of information, a configuration that a sensor is provided at
an end portion of the robot hand has been proposed.
[0003] When a sensor that combines a proximity sensor and a tactile
sensor is used as the sensor provided at the end portion of the
robot hand, further detailed information related to the object can
be obtained and more specific control of the robot hand can be
performed.
[0004] In the proximity sensor, a distance is measured by
transmitting an ultrasonic wave to a measurement target (the
object) and receiving the ultrasonic wave reflected and returned
from the measurement target. Thus, there has been a problem that,
when the distance from the measurement target is too short, the
interval between the transmission and the reception becomes too
short and it is difficult to detect the distance. Thus, with a
configuration of performing a contact determination by using a
distance, which is described in Japanese Patent Laid-Open No.
2012-141256, it is difficult to determine whether the distance from
the target is significantly short or there is a contact with the
target when the distance is too short.
[0005] On the other hand, in the tactile sensor, to detect a
pressure from the target, a certain dynamic range needs to be
maintained. Thus, with a configuration that a sensor for pressure
measurement is used to perform a contact determination, which is
described in Japanese Patent Laid-Open No. 2012-215533, it is
difficult to accurately detect a change in an imperceptible
pressure in a contacting region.
[0006] In this manner, with a sensor combining a proximity sensor
for detecting a distance from a nearby target by using an
ultrasonic wave and a tactile sensor for detecting a contact
strength with the target, there may be a dead zone of the sensor in
a region where the target and the sensor contact with each other.
Thus, it is difficult to accurately recognize a contact between the
target and the sensor.
SUMMARY OF THE INVENTION
[0007] The present embodiment has an object to provide a compound
sensor including a function as a proximity sensor and a function as
a tactile sensor, which can accurately recognize a contact with a
measurement target.
[0008] The compound sensor according to the present embodiment is a
compound sensor including a distance measurement unit configured to
measure a distance from a measurement target by transmitting an
ultrasonic wave and receiving the ultrasonic wave returned from the
measurement target, a pressure measurement unit configured to
measure a pressure applied from the measurement target, and a
contact detection unit configured to detect a presence of a contact
with the measurement target.
[0009] Further features will become apparent from the following
description of exemplary embodiments (with reference to the
attached drawings).
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic view for explaining a compound
sensor.
[0011] FIGS. 2A and 2B are schematic views for explaining another
example structure of a first embodiment.
[0012] FIG. 3 is a schematic view for explaining another example
structure of the first embodiment.
[0013] FIG. 4 is a schematic view for explaining another example
structure of the first embodiment.
[0014] FIG. 5 is a schematic view for explaining another example
structure of the first embodiment.
[0015] FIGS. 6A and 6B are schematic views for explaining a second
embodiment.
[0016] FIG. 7 is a schematic view for explaining the second
embodiment.
[0017] FIG. 8 is a schematic view for explaining the second
embodiment.
[0018] FIG. 9 is a schematic view for explaining the second
embodiment.
[0019] FIG. 10 is a schematic view for explaining the second
embodiment.
[0020] FIG. 11 is a schematic view for explaining a third
embodiment.
[0021] FIGS. 12A and 12B are schematic views for explaining a
fourth embodiment.
[0022] FIG. 13 is a schematic view for explaining a fifth
embodiment.
[0023] FIG. 14 is a schematic view for explaining the fifth
embodiment.
[0024] FIG. 15 is a schematic view for explaining the fifth
embodiment.
[0025] FIG. 16 is a schematic view for explaining the fifth
embodiment.
[0026] FIGS. 17A and 17B are schematic views for explaining a sixth
embodiment.
[0027] FIG. 18 is a schematic view for explaining the sixth
embodiment.
[0028] FIG. 19 is a schematic view for explaining a seventh
embodiment.
[0029] FIG. 20 is a schematic view for explaining the seventh
embodiment.
[0030] FIG. 21 is a schematic view for explaining the seventh
embodiment.
[0031] FIG. 22 is a schematic view for explaining an eighth
embodiment.
[0032] FIG. 23 is a schematic view for explaining the eighth
embodiment.
[0033] FIG. 24 is a schematic view for explaining the eighth
embodiment.
DESCRIPTION OF THE EMBODIMENTS
[0034] According to the present embodiment, in addition to a
distance measurement unit (a proximity sensor) and a pressure
measurement unit (a tactile sensor), a contact detection unit (a
contact sensor) dedicated to performing a detection when a target
contacts with a surface of the sensor is included.
[0035] In the following, embodiments will be described with
reference to the drawings. It is noted that the embodiments are not
limited to these embodiments and various modifications and changes
may be made within the scope.
First Embodiment
[0036] A compound sensor according to an embodiment will be
described with reference to FIG. 1. FIG. 1 is a schematic view
illustrating the compound sensor including a proximity and a
contact. In FIG. 1, 10 represents a robot hand end portion, 100
represents a compound sensor, 101 represents a distance measurement
unit (a proximity sensor), 102 represents a pressure measurement
unit (a tactile sensor), 103 represents a contact detection unit (a
contact sensor), 99 represents a target (an object), 201 represents
a distance measurement signal, 202 represents a pressure
measurement signal, and 203 represents a contact detection
signal.
[0037] The present embodiment is characterized in that each
compound sensor 100 includes the contact detection unit 103
dedicated to detecting a contact with a target, in addition to the
distance measurement unit 101 and pressure measurement unit
102.
[0038] The distance measurement unit 101 has a function for
generating an ultrasonic wave and transmitting the ultrasonic wave
toward the target 99. The ultrasonic wave irradiated to the target
99 is reflected on the surface of the target with an acoustic
impedance difference on an interface of the target. A part of the
ultrasonic wave reflected by the target 99 returns to the distance
measurement unit 101. The distance measurement unit 101 has a
function for receiving the returned ultrasonic wave and measuring a
period of time (time interval) from the time of transmission and
the time of reception. Since the time interval t is from the
transmission to reception corresponding to a length of a path that
the ultrasonic wave propagates, the distance to the target can be
measured by measuring the time interval t. The distance measurement
unit 101 has a function for calculating the distance to the target
based on the time interval t and outputting a distance measurement
signal 201.
[0039] Here, since the generated ultrasonic wave has a constant
time duration, it becomes difficult to measure the distance when
the time interval becomes equal to or smaller than the duration.
Further, the measurable time interval may sometimes be extended
because of a noise caused by a drive signal used in transmission
and ringing characteristics of a transmission/reception unit.
[0040] In a case where the distance measurement unit 101 is used in
a robot hand, it is preferable to have a specification that allows
to measure a distance shorter than a several centimeters. Further,
as an ultrasonic wave transmission/reception unit in a distance
measurement unit 101, any device may be used as long as the
transmission and reception of the ultrasonic wave can be executed
and, for example, it may be easily realized by using a
piezoelectric body. Further, a unit for measuring a time interval t
of the ultrasonic wave transmission and reception and outputting a
signal may be easily realized with a microcomputer or a combination
of an analog circuit and a logic circuit.
[0041] The pressure measurement unit 102 has a function to output
the pressure measurement signal 202 according to a pressure level
when contacting with the target. As the pressure measurement unit
102, any device which can measure the pressure applied from the
target 99 can be used and, for example, it can be easily realized
by using a piezoelectric body. When the compound sensor is provided
to a robot hand end portion 10 or the like and used to hold an
object, it is needed to accurately recognize a degree of a grip
force (pressure level) applied from the hand to the object and
control the grip force to be applied in a most preferable manner.
Thus, the measurable range of the pressure needs to be a wide
dynamic range and a sensitivity setting of the pressure measurement
unit 102 needs to be set based on a maximum grip force. Therefore,
in the pressure measurement unit 102, resolution of detecting an
imperceptible pressure cannot be made too high.
[0042] The contact detection unit 103 detects a contact between the
target 99 and sensor 100 and outputs a contact detection signal
203. To only detect whether there is a contact between the target
99 and the sensor 100, the contact detection unit 103 has a quite
high sensitivity for a pressure in a beginning of a contact by an
object. On the other hand, when the pressure becomes a little
larger, detected signals are saturated and the sensitivity
characteristics become a level which cannot be used in normal
pressure measurement. In other words, since the sensor is
saturated, the contact detection unit 103 does not perform a
detecting operation when a large pressure is applied after a
contact with the object. In this manner, the smaller pressure side
of a pressure detection range of the pressure measurement unit 102
and the lager pressure side of a pressure detection range of the
contact detection unit 103 partially overlap so that the pressure
detection ranges are complemented by each other.
[0043] The contact detection unit 103 may be realized with any
device, which can output a contact detection signal 203 when a
target 99 contacts with a surface of the sensor 100. More
specifically, the contact detection unit 103 may be easily realized
by providing a configuration that includes a membrane, which is a
thin film, and detects an imperceptible distortion of the membrane
when an imperceptible pressure is applied to the membrane.
[0044] As described above, the present embodiment has a
characteristic that the pressure measurement unit 102 having a
detection sensitivity range and the contact detection unit 103
having a different detection sensitivity range are separately
provided. Thus, in addition to the distance measurement between the
target 99 and the sensor 100 before contacting with each other and
a pressure applied from the target 99 to the sensor 100 after
contacting with each other, it can be detected whether the target
99 has contacted with the surface of the sensor 100.
[0045] As described above, according to the present embodiment, a
compound sensor having a proximity sense and a tactile sense, which
can accurately recognize a contact with a target, can be
provided.
[0046] Other example structures related to the present embodiment
will be described with reference to FIGS. 2A to 10. In FIG. 2A, an
output signal switching unit 104 is included. In the output signal
switching unit 104, based on the contact detection signal 203
obtained by the contact detection unit 103, the distance detection
signal 201 and pressure measurement signal 202 are switched as a
non-output signal and output as an output signal 203. More
specifically, when the contact detection signal 203 has detected a
contact, the distance detection signal 201 is made in a non-output
signal state and the pressure measurement signal 202 is output as
the output signal 203. On the other hand, when the contact
detection signal 203 has detected a non-contact condition, the
distance detection signal 201 is output as the output signal 203
and the pressure measurement signal 202 is made in a non-output
signal state.
[0047] With a configuration illustrated in FIG. 2A, since a
contact/non-contact condition can be determined only by referring
to the distance detection signal 201 and pressure measurement
signal 202, a process on the distance detection signal 201 and
pressure measurement signal 202 based on the contact detection
signal 203 is not needed to perform outside and a process on the
output signal from the sensor can be reduced in the system
side.
[0048] Another example structure will be described with reference
to FIG. 2B. In FIG. 2B, it is characterized that the distance
detection signal 201 and pressure measurement signal 202 are used
for the detection of a contact, in addition to the detection in the
contact detection unit 103. More specifically, in a case where the
distance detection signal 201 is a minimum detectable distance, the
pressure measurement signal 202 is a minimum detectable pressure,
and the contact detection unit 103 detects a contact, a contact
determination signal 204 is output from a contact determination
unit 105. With the configuration illustrated in FIG. 2B, since a
contact is detected based on a plurality of pieces of information,
a false detection of a contact can be reduced and a contact with a
target can be surely detected.
[0049] Other example structures will be further described with
reference to FIGS. 3 and 4. The example structure illustrated in
FIG. 3 is characterized by that a unit for switching a distance
detection mode 301, a pressure detection mode 302, and a contact
detection mode 303 is included. As illustrated in FIG. 4, in a
distance detection mode 301, the distance measurement unit 101 and
contact detection unit 103 are active and the pressure measurement
unit 102 is inactive. On the other hand, in the pressure detection
mode 302, the pressure measurement unit 102 and contact detection
unit 103 are active, and the distance measurement unit 101 is
inactive. More specifically, when the pressure measurement signal
202 indicates a minimum detectable pressure and the distance
detection signal 201 is not a minimum detectable distance, the
distance detection mode is selected. On the other hand, when the
distance detection signal 201 is the minimum detectable distance
and the pressure measurement signal 202 is not the minimum
detectable pressure, the pressure detection mode is selected.
Further, when the distance detection signal 201 is the minimum
detectable distance and the pressure measurement signal 202 is the
minimum detectable pressure, the distance measurement unit 101,
pressure measurement unit 102, and contact detection unit 103 are
active.
[0050] FIG. 4 schematically illustrates, as an example, operation
by the distance measurement unit 101, pressure measurement signal
202, contact detection unit 103, and contact determination unit 105
when the modes are switched from the contact detection mode 303,
the distance detection mode 301, the contact detection mode 303,
the pressure detection mode 302, and then the contact detection
mode 303 in order. FIG. 4 illustrates that the periods indicated by
the hexagonal shapes represent that the objective units are
operating, and the periods indicated by the lines represent that
the objective units have stopped operating. Further, the
configuration in FIG. 4 is illustrated assuming that the compound
sensor has the configuration of FIG. 2B; however, the present
embodiment is not limited to this example and other configurations
may be used in the same manner.
[0051] In FIG. 3, since unnecessary operation in the units can be
stopped, the entire consumption power can be reduced. Further,
considering a case where a drive signal generated by the distance
measurement unit 101 cases noise during the detection by the
pressure measurement unit 102, deterioration of the pressure
detection accuracy can be reduced. On the other hand, in a case
where a reference signal used in the detection by the pressure
measurement unit 102 causes noise during the detection by the
distance measurement unit 101, deterioration of the pressure
detection accuracy can be reduced.
[0052] Here, in the present embodiment, a case that each detection
unit obtains a minimum detectable distance or a minimum detectable
pressure has been explained as an example for illustrative
purposes; however, the present embodiment is not limited to this
example. A case where the signal becomes close to the minimum
detectable distance or the minimum detectable pressure within the
detection range of each detection unit can be used as a
determination standard, and it may be optimally set, according to a
usage condition, at which degree it becomes closer the
determination is to be made. A compound sensor having a high
responsiveness can be provided by making a determination when the
signal becomes closer to the minimum detectable distance or the
minimum detectable pressure.
[0053] A robot hand system using the compound sensor according to
the present embodiment will be described with reference to FIG. 5.
In FIG. 5, the compound sensor 100 according to the present
embodiment is provided at an end portion of a finger part 20. The
finger part 20 is supported by a finger part drive unit 30 on a
fixed part 40. The finger part drive unit 30 internally includes a
driving mechanism such as a motor and a mechanism to operate in
directions of the arrows A and B based on a drive signal 61
received from outside. The output signals 201, 202, and 203 from
the compound sensor 100 are input to a finger position calculation
unit 50, and the finger position calculation unit 50 calculates a
position coordinate of a location (end portion 10) where the
compound sensor 100 of each finger part 20 is provided based on the
input signals and outputs the position coordinate as a finger part
position information 51. The finger part control unit 60 generates
a finger part drive signal 61 that instructs to drive the finger
part 20, based on the finger part position information 51. For
example, when the distance to the target 99 is large, a process to
move the finger part 20 closer is performed and, when a force of
the finger part 20 to hold the target 99 is weak, the force is made
greater or the position of the finger part 20 is adjusted so that
the target 99 can be held securely. In FIG. 5, since the compound
sensor 100 that can accurately recognize whether there is a contact
with the end portion 10 of the finger part 20, the distance, and
the pressure is provided, the finger part 20 can be controlled
toward the target 99 in a most appropriate manner.
[0054] Here, in FIG. 5, a configuration including two finger parts
20 and a single drive unit 30 provided to the finger part 20 is
described; however, the present embodiment is not limited to this
configuration. There may be more than two finger parts 20, or the
drive unit 30 of the finger part 20 may have fingers including
multiple joints.
Second Embodiment
[0055] A second embodiment relates to configurations of the
distance measurement unit 101, pressure measurement unit 102, and
contact detection unit 103. Other configurations are the same as
those in the first embodiment. The second embodiment will be
described with reference to FIGS. 6 to 10.
[0056] The second embodiment is characterized by that the distance
measurement unit 101, pressure measurement unit 102, and contact
detection unit 103 are composed by using a piezoelectric film, more
specifically, a thin membrane having a thin film of a piezoelectric
body.
[0057] FIGS. 6A and 6B are schematic perspective views for
explaining the compound sensor according to the present embodiment.
In FIGS. 6A and 6B, 400 represents a substrate, 401, 402, and 403
represent membranes, 404 represent thin film piezoelectric bodies,
405 represents through holes, and 406 represents an elastic
body.
[0058] The membranes 401, 402, and 403 are provided on a surface of
the substrate 400 having the plurality of through holes 405. To the
membranes 401, 402, and 403 on the through hole 405, the thin
piezoelectric bodies 404 are provided respectively. The respective
membranes 401, 402, and 403 composing the distance measurement unit
101, pressure measurement unit 102, and contact detection unit 103
basically have the same configuration while the size of the through
hole 405, the thickness of the piezoelectric body 404, and the
thickness of the membrane, and the like are adjusted in a most
preferable manner. The membranes 401, 402, and 403 may be made of
anything such as a silicon nitride film, silicon, metal, and the
like as long as that necessary mechanical characteristics can be
obtained. Further, the substrate 400 may be made of anything such
as silicon, glass, metal, glass epoxy, or the like, as long as
mechanical characteristics and an adhesiveness to the membrane, and
an insulation property can be obtained.
[0059] In the membrane 401 of the distance measurement unit 101, an
ultrasonic wave is transmitted by applying a drive voltage to the
piezoelectric thin film 404 and vibrate the membrane 401. On the
other hand, as a reflected ultrasonic wave achieves and vibrates
the membrane 401, and the reception is performed by detecting a
voltage generated in the piezoelectric thin film 404.
[0060] On the membrane 402 of the pressure measurement unit 102 and
the membrane 403 of the contact detection unit 103, the elastic
body 406 is provided. With the elastic body 406, pressure applied
to the target 99 can be evenly transferred to the membranes 402 and
403. Further, with the elastic body 406, the membranes 402 and 403
may also be protected from the target 99.
[0061] The membrane 403 of the contact detection unit 103 is made
softer and can be widely deformed by a smaller pressure, compared
to the membrane 402 of the pressure measurement unit 102. More
specifically, the membrane 403 may be easily realized with a
configuration such that the vibrating membrane of the membrane is
made thinner or the size of the membrane is made larger.
[0062] In the configuration using the membranes according to the
present embodiment, the membranes may be formed on the same
substrate 400 in a same manufacturing process and easily integrated
in a single chip. In addition, the low-cost compound sensor can be
easily realized. Further, since circuits needed in each unit can
easily be integrated on a substrate, a smaller compound sensor can
be provided.
[0063] The compound sensor according to the present embodiment can
provide a compound sensor including a proximity sense and a tactile
sense which can be easily integrated and accurately recognize a
contact with the target.
[0064] Here, in FIG. 6A, nothing is provided on the membrane 401 of
the distance measurement unit 101, and the membrane 401 of the
distance measurement unit 101 are made to directly contact with the
air; however, the present embodiment is not limited to this
example. As illustrated in FIG. 6B, there may be a configuration in
which the elastic body 406 is provided on the membrane 401 on the
distance measurement unit 101. Since the elastic body 406 is
provided to cover all over the substrate 400, this can make its
fabrication easier. Further, since a function that the surface of
the membrane 401 is protected by the elastic body 406 is added,
this can prevent the membrane 401 from being broken when contacting
with the target 99. Here, the elastic body 406 used in this example
is preferably made of a material that passes an ultrasonic wave
therethrough and hardly gives an affect to the mechanical
characteristics of the membrane 401 (a material having modulus of
smaller longitudinal elasticity compared to the material of the
membrane is further suitable). The material may be selected from
silicone rubber, ethylene-propylene rubber (EPDM), dimethyl
polysiloxane (PDMS), urethane rubber, and the like.
[0065] Further, as illustrated in FIG. 7, the thickness of the
elastic body 406 on the membrane 401 of the distance measurement
unit 101 is preferably made thinner than the thickness of the
elastic body 406 on the membrane 402 and the membrane 403. With
this configuration, attenuation of the ultrasonic wave in the
elastic body 406 can be minimized when the ultrasonic wave is
transmitted and received, a large transmission/reception signal can
be obtained and a more accurate distance measurement can be
performed.
[0066] Further, as illustrated in FIG. 8, it is preferable that the
load distribution plate 407 is provided further above the elastic
body 406 on the membrane 402 and membrane 403. Since the load
distribution plate 407 is provided and an average pressure is
applied to the sensor and a stable measurement can be performed
even in a case where the target 99 has an uneven surface shape or
pressure from the target 99 varies depending on the locations.
Further, in FIGS. 6 to 8, only one membrane 402 and one membrane
403 are provided; however, in actual, a plurality of membranes 402
and a plurality of membranes 403 are provided as groups. Here,
since the membranes are arranged with a certain intervals
therebetween because of a constraint of arrangement, there may be
an area in which there is no membrane on the substrate 400.
However, when the load distribution plate 407 is provided, the
pressure from the target 99 are collected as an amount of the
surface area of the load distribution plate 407 and even pressure
is applied to the membranes 402 and 403 regardless of the presence
of the membrane, and this allows an accurate measurement.
[0067] Another example structure of the present embodiment will be
described with reference to FIG. 9. The configuration illustrated
in FIG. 9 is characterized by that the substrate 400 does not have
the through hole 405, the membrane 401 is provided on the
supporting part 411 which is placed on the substrate 400 and is
held above the surface of the substrate 400 with a space 412. With
this configuration, even when the membrane 401 vibrates during
transmission or reception of the ultrasonic wave or the membrane
401 is deformed due to a pressure from the target 99, the membrane
401 does not interfere with the substrate 400 and the measurement
and detection operation can be performed.
[0068] In the configuration illustrated in FIG. 6, to provide a
plurality of through holes 405, the rigidity of the substrate 400
needs to be maintained and the distance between the through holes
405 needs to be made greater than a certain distance. Further, when
the through holes 405 are formed in a thick substrate 400, which
has a thickness of hundreds of micrometers, since an angle (taper)
is made in a side wall, larger intervals may be required. Thus, the
intervals between the membrane 401 is determined according to the
intervals between the through holes 405, this may be a constraint
when increasing the degree of integration.
[0069] On the other hand, in the case of the compound sensor 100 in
the configuration illustrated in FIG. 9, which is another example
structure of the present embodiment, since the through holes 405
are not needed to be provided in the substrate 400, the above
describe constraint is not applied. Thus, the membranes 401, 402,
and 403 may be provided close to one another and this helps in a
view of downsizing. In other words, since the rate of the membranes
can be made larger within a same sensor area, measurement accuracy
and detection accuracy of the sensor can be improved, and high
accurate measurement and detection can be performed.
[0070] Further, as illustrated in FIG. 10, the thickness of the
load distribution plate 407 on the membrane 403 of the contact
detection unit 103 can be made thicker, compared to the thickness
of the load distribution plate 407 on the membrane 402 of the
pressure measurement unit 102. Thus, even when the load
distribution plate 407 is displaced with a same distance vertically
with respect to the substrate 400, since the thickness of the
compressed elastic body 406 is smaller, a greater pressure is
applied in the side of the membrane 403 of the contact detection
unit 103 and the contact detection can be more accurately
performed.
Third Embodiment
[0071] A third embodiment relates to configurations of the distance
measurement unit 101, pressure measurement unit 102, and contact
detection unit 103. Other configurations are the same as those in
FIG. 9. The third embodiment will be described with reference to
FIG. 11.
[0072] The third embodiment is characterized by that the distance
measurement unit 101, pressure measurement unit 102, and contact
detection unit 103 are formed by using static capacitance between
electrodes 421 provided on the thin membranes 401, 402, and 403 and
opposite electrodes 422 provided on the substrate 400.
[0073] FIG. 11 is a schematic view for explaining the compound
sensor according to the present embodiment. In FIG. 11, 421
represents first electrodes, and 422 represents second
electrodes.
[0074] The membranes 401, 402, and 403 according to the present
embodiment are supported by supporting parts 411 provided on the
substrate 400. The first electrodes 421 are provided on the
membranes 401, 402, and 403 so as to be deformed integrally with
the membranes 401, 402, and 403. On the substrate 400 facing to the
first electrodes 421, the second electrodes 422 are provided. The
sensor is used in a condition that, a certain potential difference
Vb is always applied between the first electrode 421 and second
electrode 422, the membranes 401, 402, and 403 are deformed toward
the substrate 400, and tension is always applied toward the
substrate 400.
[0075] In the distance measurement unit 101, by applying an
alternating potential difference between the first electrode 421
and second electrode 422, the membrane 401 is vibrated and an
ultrasonic wave is transmitted. On the other hand, when the
ultrasonic wave reaches the membrane 401, the membrane 401
vibrates, and the static capacitance between the first electrode
421 and second electrode 422 changes. Since a certain potential
difference Vb is always being applied between the first electrode
421 and second electrode 422, a magnitude of the received
ultrasonic wave can be measured by detecting a minute electric
current caused by the change in the capacitance.
[0076] In the pressure measurement unit 102, the amount of the
deformation of the membrane 402 changes when a pressure is applied
by the target 99, and this results in that a static capacitance
value between the first electrode 421 and second electrode 422
changes. By measuring the static capacitance value, the applied
pressure can be recognized. A method for measuring the static
capacitance value can be easily realized by using a C-V conversion
circuit, or the like. Further, a change in the capacitance may be
further accurately detected when a frequency that does not vibrate
the membrane 402 is selected, a frequency of a reference signal is
applied, an induced current caused thereby is measured, and the
detection is performed with the frequency of the reference
signal.
[0077] The contact detection unit 103 is designed so that the
membrane 403 deforms in a considerably larger manner, compared to
the membrane 402, which deforms in the pressure measurement unit
102, when a same pressure is applied. More specifically, it can be
preferably adjusted by making the thickness of the membrane 403
thinner or making the diameter of the membrane 403 larger. With
this, since the configuration can be realized simply by changing an
in-plane pattern of the membrane or changing the thickness of the
thin film to be layered as the membrane.
[0078] In addition to the method of changing the deformation amount
of the membrane 403 with respect to the input pressure, a method of
making the change in the static capacitance larger by reducing the
height of the supporting part 411 and making the space between the
first electrode 421 and second electrode 422 smaller, even with the
same deformation amount of the membrane 403. With this, since the
detection signal itself can be enlarged, an SN ratio can be
improved, and the detection accuracy can be further improved.
[0079] Further, the same effect can be obtained by increasing a
direct potential difference applied between the first electrode 421
and second electrode 422 and making an initial deformation of the
membrane 403 larger, compared to the case that the height of the
supporting part 411 is lowered. In addition, since an electric
field density between the first electrode and second electrode is
increased, when the static capacitance is detected, a larger signal
can be obtained, and the detection accuracy may be improved.
[0080] Here, in a sensor of a static capacitance type, when the
electrostatic attractive force generated by the potential
difference between the first electrode and second electrode
excesses the magnitude of a restoration force made by a spring in
the membrane 403, the membrane 403 is pulled toward the substrate
400 (this is called "pull in"). Thus, in the sensor of the static
capacitance type, as the sensitivity with respect to the applied
pressure is made greater, the upper limit of the pressure that the
pull-in is generated becomes reduced and the maximum detectable
magnitude is reduced. Thus, the pressure measurement unit 102,
which detects up to a large pressure, and the contact detection
unit 103, which detects an imperceptible pressure when contacting
with the target, are provided as different units, the measurement
and detection thereof can have the most appropriate characteristics
respectively, like the present embodiment.
[0081] According to the present embodiment, since the sensor of the
static capacitance type is used, the distance measurement unit 101,
pressure measurement unit 102, and contact detection unit 103 can
be easily integrated on the substrate 400 and the entire compound
sensor can be downsized. Further, since only the electrodes 421 and
422 need to be provided and the configuration becomes simple, the
sensor can be realized by a more general semiconductor process and
the manufacturing cost can be easily reduced, compared to the
configuration according to the second embodiment.
[0082] As described above, according to the present embodiment, a
compound sensor having a proximity sense and a tactile sense that
can be easily downsized, have a simple configuration, and
accurately recognize a contact with a target can be provided.
[0083] Here, the present embodiment has described that all the
distance measurement unit 101, pressure measurement unit 102, and
contact detection unit 103 are all sensors of a static capacitance;
however, the present embodiment is not limited to this example.
There may be a configuration that the sensor in which a thin-film
piezoelectric body 404 is formed on a membrane as described in the
second embodiment may be provided in a mixed manner.
Fourth Embodiment
[0084] A fourth embodiment relates to a configuration of the
contact detection unit 103. Other configurations are the same as
those of the third embodiment. The fourth embodiment will be
described with reference to FIGS. 12A and 12B.
[0085] The fourth embodiment is characterized by that a presence or
an absence of a contact between the membrane 403 and substrate 400
is used for a contact detection by the contact detection unit
103.
[0086] In FIGS. 12A and 12B, 423 represents a contact detection
electrode.
[0087] According to the present embodiment, a contact detection
electrode 313 is provided under the membrane 403. When the target
99 contacts with the surface of the sensor, the pressure is applied
to the membrane 403 in the contact detection unit 103. Between the
first electrode 421 on the membrane 403 and the second electrode
422, a potential difference Vb is applied and an electrostatic
attractive force is always being applied. Here, the restoration
force of a spring is simply proportional to the distance when the
distance between the electrodes becomes smaller; however, it should
be focused on that the electrostatic attractive force is inversely
proportional to the square of the distance when the distance
between the electrodes becomes smaller, and the electrostatic
attractive force rapidly increases.
[0088] According to the present embodiment, it is adjusted so that,
when an external force is applied to the membrane 403 and the
membrane 403 deforms, the electrostatic attractive force easily
exceeds the restoration force of the spring in the membrane 403,
and the membrane 403 contacts with the lower electrode at once.
With this configuration, when the target 99 contacts with the
surface of the sensor 100, the contact detection electrode 423
immediately under the membrane 403 and the second electrode 422 on
the substrate 400 are electrically contacted, the contact with the
target 99 can be easily detected by measuring a resistance value
between the contact detection electrode 423 and second electrode
422.
[0089] Further, as illustrated in FIG. 12B, there may be a
configuration that the second electrode 422 and contact detection
electrode 423 are integrally formed. This simplifies the
configuration since it is realized by simply forming an electrode
on a lower surface (the surface facing to the substrate 400) of the
membrane 403. This configuration is characterized by that a
resistance R is inserted between the first electrode 421 and second
electrode 422, and in a path of a unit 500 that applies a potential
difference Vb between the electrodes. With this configuration, even
when the first electrode 421 having a certain potential difference
contacts with the second electrode 422 (contact detection electrode
423), an excessive current can be prevented and a breakage or a
malfunction of the electrodes, conductive lines, and a potential
difference generating unit can be prevented.
[0090] Further, there may be a configuration that a piezoresistive
element is provided on the membrane, as a substitute for the
electrodes 421 and 422. A contact can be detected by detecting a
change in piezoresistive values caused by an imperceptible
deflection when the target 99 contacts with the sensor surface and
the membrane 403 deforms. Further, when more than one
piezoresistive elements are provided and Wheatstone bridge is
formed, the presence of a contact can be more accurately detected
whether.
Fifth Embodiment
[0091] A fifth embodiment relates to an arrangement of the distance
measurement unit 101, pressure measurement unit 102, and contact
detection unit 103. Other arrangements are the same as those in any
one of the first to fourth embodiments. The fifth embodiment will
be described with reference to FIGS. 13 to 16.
[0092] The configuration illustrated in FIG. 13 is characterized by
that the contact detection unit 103 is provided in a center of the
compound sensor 100. With this configuration, the compound sensor
100 provided at the end portion of the robot hand approaches, as
facing straight, to the target 99 having a curved surface, the
contact detection unit 103 firstly contacts with the target 99.
Thus, the contact with the target 99 can be more quickly
detected.
[0093] Further, in FIG. 13, the distance measurement unit 101 is
formed in a plurality of annular shapes and provided so as to
surround the contact detection unit 103. When transmitting an
ultrasonic wave, the distance measurement unit 101 drives the
separate annular element respectively with a time lag so that the
location on which the ultrasonic wave is made to focus can be
adjusted. In a same manner, when an ultrasonic wave is received,
signals detected by respective separate annular elements are added
with a time lag, and this improves the resolution within the
surface at a certain distance. With such a configuration, the beam
of the ultrasonic wave to be transmitted or received within a
certain distance can be narrowed, the distance can be measured more
accurately.
[0094] In FIG. 13, the pressure measurement unit 102 is provided at
remained spaces in four corners on the substrate 400. Thus, with
the configuration illustrated in FIG. 6A, the sensors of the three
types can be efficiently arranged in a small area and a downsized
compound sensor can be provided.
[0095] Another example structure of the present embodiment will be
described with reference to FIG. 14. The configuration illustrated
in FIG. 14 is characterized by that the contact detection unit 103
is provided in outer areas in the compound sensor 100. When the
compound sensor 100 provided at the end portion of the robot hand
approaches to the target 99 in a tilted manner, the contact
detection unit 103 firstly contacts with the target 99. Thus, the
contact with the target 99 can be more quickly detected.
[0096] With reference to FIGS. 13 and 14, the configuration that
the contact detection unit 103 is provided at the center and the
configuration that the contact detection unit 103 is provided in
four corners have been respectively described; however, the present
embodiment is not limited to these examples and the above
configuration may be combined. This makes a preferable
configuration since a contact with the target 99 can be detected
more quickly even when the target 99 is facing straight or
tilted.
[0097] FIG. 15 illustrates a configuration that the pressure
measurement unit 102 and contact detection unit 103 are provided in
periphery areas of the substrate 400. This makes the configuration
simple in which the load distribution plate 407 having a round
shape cut out therefrom (which is illustrated with dotted lines in
FIG. 15) is provided in the outer areas on the substrate 400, in a
case of the configuration including the elastic body 406 and load
distribution plate 407. Further, since the load distribution plate
407 is provided, the pressure from the target 99 can be efficiently
transferred to the pressure measurement unit 102 and contact
detection unit 103 and accurate measurement can be performed. In
addition, the load distribution plate 407 is not placed above the
distance measurement unit 101 provided in the center of the
substrate 400, distance measurement can be performed without having
interference in the transmission and reception of an ultrasonic
wave. With the configuration illustrated in FIG. 15, a compound
sensor that can perform an accurate detection with a simple
configuration can be provided.
[0098] On the other hand, as illustrated in FIG. 16, there may be a
configuration that the pressure measurement unit 102 and contact
detection unit 103 are provided in the center of the substrate 400.
This makes the configuration simple in which the load distribution
plate 407 in a round shape (which is illustrated with a dotted line
in FIG. 16) is provided in the center of the substrate 400, in a
case of the configuration including the load distribution plate
407. Further, since the load distribution plate 407 is provided,
the pressure from the target 99 can be efficiently transferred to
the pressure measurement unit 102 and contact detection unit 103
and high-accurate measurement can be performed. In addition, since
the load distribution plate 407 is not placed above the distance
measurement unit 101 provided in the outer areas on the substrate
400, distance measurement can be performed without having
interference in the transmission and reception of an ultrasonic
wave. With the configuration illustrated in FIG. 16, the sensors of
the three types can be efficiently arranged on the substrate 400
and a compound sensor that can perform accurate detection with a
simple configuration can be provided.
[0099] With reference to FIGS. 15 and 16, the configurations that
the load distribution plate 407 is provided on the substrate 400
via the elastic body 406 have been described. Here, the area where
the elastic body 406 is placed may be only under the load
distribution plate 407 or may be the entire area on the substrate
400, and any of the example structures may be used.
Sixth Embodiment
[0100] A sixth embodiment relates to a type of the measurement unit
101. Other configurations are the same as those in any one of the
first to fifth embodiments. The sixth embodiment will be described
with reference to FIGS. 17A, 17B, and 18.
[0101] The sixth embodiment will be described by using the
configuration of the static capacitance type sensor including a
membrane and opposite electrodes, which has been described in the
third embodiment. In FIGS. 17A, 17B, and 18, 108 represents a shear
force detection unit, 108a represents an ultrasonic wave
transmitting/receiving element, 108b represents an ultrasonic wave
receiving element, X indicates directions of sliding, 408
represents a membrane, and 409 represents a protrusion of the load
distribution plate 407. In these drawings, the pressure measurement
unit 102 and contact detection unit 103 on the same substrate 400
are omitted and only the distance measurement unit 101 and shear
force detection unit 108 are illustrated.
[0102] The sixth embodiment includes a unit 108 (slide sense
sensor) for detecting a shear force in a horizontal direction with
respect to the substrate surface, in addition to the proximity
sense, tactile sense, and tactile sense. Here, the description will
be given with reference to the configuration according to the third
embodiment. The shear force detection unit 108 is composed of the
element 108a that transmits and receives an ultrasonic wave and an
element 108b that receives an ultrasonic wave. On the membrane 408
in the shear force detection unit 108, the load distribution plate
407 is provided via the elastic body 406. To the load distribution
plate 407 above the element 108a that transmits and receives an
ultrasonic wave, the protrusion 409 is provided.
[0103] An ultrasonic wave 211 is transmitted from the ultrasonic
wave transmitting/receiving element 108a toward a lower face of the
load distribution plate 407. The ultrasonic wave is reflected by
the protrusion 409 of the load distribution plate 407. The
reflected ultrasonic wave 212 is received by the ultrasonic wave
transmitting/receiving element 108a and the ultrasonic wave
receiving element 108b provided near the ultrasonic wave
transmitting/receiving element 108a. When a shear force (a slide
force) in a horizontal direction with respect to the substrate
surface is generated between the surface of the target 99 and the
surface of the compound sensor 100, since the elastic body 406 is
flexible and slightly deforms, and the load distribution plate 407
moves in the horizontal direction with respect to the substrate
(for example, the directions of arrow X in FIG. 17A). When the load
distribution plate 407 moves in a parallel manner, the position of
the protrusion 409 changes and the magnitude or a delay time of the
ultrasonic wave received by the transmitting/receiving element 108a
and receiving element 108b changes. Based on those received
signals, the amount of the parallel displacement of the load
distribution plate 407 is detected and, thus, the shear force
applied from the target 99 to the surfaces of the compound sensor
100 can be detected.
[0104] The sixth embodiment is characterized by that it is switched
whether to activate the distance detection unit 101 or shear force
detection unit 108, based on the contact detection signal 203 from
the contact detection unit 103. More specifically, when a contact
state is not detected, the distance detection unit 101 is made
active and the shear force detection unit 108 is stopped. On the
other hand, when a contact state is detected, the distance
detection unit 101 is stopped and the shear force detection unit
108 is made active. Since the distance detection unit 101 and shear
force detection unit 108 both make a measurement by transmitting
and receiving ultrasonic waves, a leakage of a drive signal or a
transmitted ultrasonic wave from detection operation in one side
may affect the detection in the other side. In the configuration
according to the present embodiment, since the contact detection
unit 103 is provided, a unit to be activated and a unit to be
stopped can be selected as described above. This prevents that an
ultrasonic wave used in the measurement in one side affects in the
measurement in the other side, and the high-accurate measurement
can be performed.
[0105] Here, with reference to FIG. 17A, a configuration that the
load distribution plate 407 has the protrusion 409 has been
described; however, the present embodiment is not limited to this
example, and a similar effect may be obtained with a configuration
that an air gap 415, which is not filled with the elastic body 406,
is provided at the area of the protrusion 409, for example. This
configuration uses characteristics that the ultrasonic wave is
reflected by a border having a large difference of acoustic
impedance and can be realized with a simple configuration since
only the area to be filled with the elastic body 406 is
adjusted.
[0106] Another example structure of the present embodiment will be
described with reference to FIG. 17B. In FIG. 17B, the load
distribution plate 407 has holes 410. The shear force detection
unit 108 is composed of the transmitting/receiving element 108a,
and the hole 410 is provided so that a half of the
transmitting/receiving element 108a is covered by the load
distribution plate 407. When a shear force is applied from the
target 99 to the surface of the sensor 100 and the load
distribution plate 407 is displaced in the direction of the arrow X
for example, the positions of the holes 410 are shifted and the
size of the openings changes. This causes a change in the magnitude
of the ultrasonic wave 212 reflected by the load distribution plate
407 after the ultrasonic wave 211 is transmitted. Based on the
information, the shear force can be measured. The configuration
illustrated in FIG. 17B can be realized in a further simple manner,
since the shear force can be detected only by providing the holes
in the load distribution plate 407.
[0107] As described above, according to the present embodiment, a
compound sensor having a proximity sense and a tactile sense that
can be easily downsized, have a simple configuration, and more
accurately recognize a contact with a target can be provided.
[0108] Here, with reference to FIGS. 17A, 17B and 18, the shear
force in one direction has been described for illustrative
purposes; however, the present embodiment is not limited to this
configuration and may be applied to measurement of shear force in
two of in-plane directions in the similar manner. In such a case,
the detection of the two of the in-plane directions can be easily
realized by adjusting the shape of the protrusion 409 in FIG. 17A
or the shape of the holes 410 in FIG. 17B, and the configuration
hardly needs to be changed.
[0109] Further, with reference to FIGS. 17A and 17B, the
configuration that the pressure measurement unit 102, contact
detection unit 103, and shear force detection unit 108 are provided
as separate components; however, the present embodiment is not
limited to this example. In the configuration, as illustrated in
FIGS. 17A and 18, that the load distribution plate 407 does not
have the holes, the shear force detection unit 108 may also be used
as the pressure measurement unit 102 or contact detection unit 103.
In such a case, the load distribution plate 407 may easily be used
in both purpose by being switched in time-sharing bases between a
case of detecting a shear force and a case of performing pressure
detection or contact detection. With this configuration, it may
take more data obtaining intervals; however, a compound sensor that
is further downsized and can perform a slide since (shear force
detection) can be provided.
[0110] Here with reference to FIGS. 17A and 17B, description has
been given using the configuration of a static capacitance type
sensor, which includes a membrane and opposite electrodes and
described in the third embodiment; however, the present embodiment
is not limited to this example. The present embodiment may be
applied to other configurations including the configuration
described in the second embodiment.
Seventh Embodiment
[0111] A seventh embodiment relates to an arrangement of the
distance measurement unit 101. Other arrangements are the same as
those in any one of the second to sixth embodiments. The seventh
embodiment will be described with reference to FIGS. 19 to 21.
[0112] The seventh embodiment is characterized by that the distance
measurement unit 101 is provided on the load distribution plate
407.
[0113] FIGS. 19 to 21 are schematic views for explaining the
compound sensor according to the present embodiment. Here, the
description will be given with a configuration of the static
capacitance type sensor, which is composed of a membrane and
opposite electrodes and described in the third embodiment. In these
drawings, 430 represents a second substrate.
[0114] According to the present embodiment, as illustrated in FIG.
19, a movable second substrate 430 is provided on a fixed substrate
(which is referred to as a first substrate, for the sake of
simplicity, in the present embodiment) 400 via the elastic body
406. In the configuration according to the present embodiment, the
second substrate 430 additionally includes a function as the load
distribution plate 407. On a surface opposite to the side facing to
the first substrate 400 (in the side of the target 99), the second
substrate 430 (load distribution plate 407) is provided with the
distance measurement unit 101. In other words, on a first
substrate, a second substrate is provided via an elastic body, and
the distance measurement unit is provided on a surface of the
second substrate opposite to the surface facing to the first
substrate. On the other hand, on the first substrate, only the
pressure measurement unit 102 and contact detection unit 103 are
provided. When the distance from the target 99 is measured, the
distance measurement unit 101 on the second substrate 430 transmits
and receives ultrasonic waves and the distance is measured.
Further, after the target 99 contacts with the surface of the
compound sensor 100, since the second substrate 430 serves as the
load distribution plate 407, a pressure is applied to the pressure
measurement unit 102 and contact detection unit 103 provided on the
first substrate 400 so that pressure measurement and contact
measurement can be performed.
[0115] In the configuration illustrated in FIG. 19, since the
distance measurement unit 101 is placed on the second substrate
430, which serves as the load distribution plate 407, an area in
which sensors can be placed is nearly twice as that in the
configuration including a single substrate. Thus, the sensitivity
of each sensor can be improved and a compound sensor that can
perform higher-accurate detection can be provided.
[0116] Further, since the distance measurement unit 101, which
transmits and receives ultrasonic waves is not provided above the
pressure measurement unit 102 and contact detection unit 103 via
the second substrate 430 therebetween, without being provided on
the same surface, transmission signals of the ultrasonic waves and
reference signals used in a capacitance detection can be shield.
Thus, crosstalk of the signals between the distance measurement
unit 101, pressure measurement unit 102, and contact detection unit
103 can be reduced, and a further accurate detection can be
performed.
[0117] Another example structure of the present embodiment will be
described with reference to FIG. 20. In FIG. 20, the pressure
measurement unit 102 and contact detection unit 103 are provided on
the rear surface (the surface in the side of the first substrate
400) of the second substrate 430. With this, since all the sensors
of the three types are provided on the second substrate 430, a
signal output line from the sensor or a power supply line to a
circuit in the sensor may be simply led from the second substrate
430. Thus, even when the area in which the sensors are provided is
enlarged, the leading of the conductive lines can be
simplified.
[0118] The present embodiment is not limited to the example
structures illustrated in FIGS. 19 and 20. As illustrated in FIG.
21, there may be a configuration in which the configurations of
FIGS. 19 and 20 are combined. In the configuration illustrated in
FIG. 21, since the area where the sensors are provided can be made
larger, a further-accurate compound sensor can be provided.
[0119] Here, description has been given using the configuration of
a static capacitance type sensor, which includes a membrane and
opposite electrodes and described in the third embodiment; however,
the present embodiment is not limited to this example. The present
embodiment may be applied, in the same manner, to other
configurations including the configuration described in the second
embodiment.
Eighth Embodiment
[0120] An eighth embodiment is related to the distance measurement
unit 101 and pressure measurement unit 102. Other configurations
are the same as those in any one of the first to seventh
embodiments. The eighth embodiment will be described with reference
to FIGS. 22 to 24.
[0121] The eighth embodiment is characterized by that the distance
measurement unit 101 and pressure measurement unit 102 are provided
as a single unit. In FIGS. 22 to 24, 106 represents a
distance/pressure measurement unit, 107 represents a
distance/pressure measurement switch unit, 205 represents a
distance/pressure measurement switch signal, 206 represents a
detection signal, 207 represents a distance/pressure measurement
output signal, 440 represents a direct potential application unit,
441 represents a switching unit, 442 represents a distance
measurement circuit, 443 represents a pressure measurement circuit,
444 represents a switching unit, 445 represents a switching unit,
and 446 represents a superposition unit.
[0122] First, FIG. 22 will be explained. The distance/pressure
measurement switch unit 107 is composed to select which measurement
operation is to be performed based on the contact detection signal
203 output from the contact detection unit 103. More specifically,
when the contact detection signal 203 changes from a contact
detection to a non-contact detection, a distance measurement
operation is performed and, when the contact detection signal 203
changes from a non-contact detection to a contact detection, a
pressure measurement operation is performed. With this
configuration, it can be judged whether the compound sensor 100
(the end portion of the robot hand 10) is moving to release the
target 99 or to hold the target 99.
[0123] The distance/pressure measurement unit 106 is composed to
detect as a distance detection unit and a pressure measurement unit
and performs one of the distance measurement and the pressure
measurement after exchanging the drive signal 205 and detection
signal 206 with the distance/pressure measurement switch unit 107.
More specifically, when distance measurement is performed, the
distance is measured by transmitting an ultrasonic wave from the
distance/pressure measurement unit 106 and receiving the reflected
and returned ultrasonic wave. Further, when pressure measurement is
performed, a deformation amount of a membrane in the
distance/pressure measurement unit 106 is detected and measured as
a pressure.
[0124] According to the present embodiment, since the distance
measurement unit and pressure measurement unit can be provided as a
single unit, a compound sensor including a proximity sense and a
tactile sense, which is further downsized and can accurately
recognize the contact with the target.
[0125] Another example structure of the present embodiment will be
described with reference to FIG. 23. Here, the description will be
given with a configuration of the static capacitance type sensor,
which is composed of a membrane and opposite electrodes and
described in the third embodiment. Based on the contact detection
signal 203 input to the distance/pressure measurement switch unit
107, the circuit to be connected to the electrode of the membrane
in the distance/pressure measurement unit 106 is switched between
the distance measurement circuit 442 and pressure measurement
circuit 443 by the switching unit 441. The static capacitance type
sensor in the distance/pressure measurement unit 106 has the other
electrode connected to the direct potential application unit 440,
and a direct potential difference Vb is applied between the first
electrode and second electrode.
[0126] When connected to the distance measurement circuit 442, a
drive signal 205 for an ultrasonic wave transmission is applied to
the electrode of the membrane, a signal 206 of the ultrasonic wave
which is reflected and returned is amplified, and the distance is
measured based on the time difference and output as a distance
measurement signal 201. On the other hand, when connected to the
pressure measurement circuit 443, a signal 206 corresponding to a
capacitance from the distance/pressure measurement unit 106 is
amplified, converted into a capacitance value, and output as a
pressure measurement signal 202. Based on the contact detection
signal 203, the switching unit 444 switches which of the respective
output signals 201 and 202 is to be output as a distance/pressure
measurement output signal 207.
[0127] Further, as illustrated in FIG. 24, there may be a
configuration that the superposition unit 446 superimposes a
reference signal 208 having a frequency which does not vibrate the
membrane to the output potential from the direct potential
application unit so that the pressure measurement circuit 443 can
amplify the signal 206 to be detected. In this case, the pressure
measurement circuit 443 can easily extract a signal corresponding
to the capacitance value by detecting the detection signal 206
using a frequency of the reference signal 208.
[0128] According to the configuration of the present embodiment,
since the contact detection unit 103 is provided, the distance
measurement unit 101 and pressure measurement unit 102 can be
provided as a single unit. This simplifies the configuration of the
sensor and a further downsized compound sensor can be provided.
[0129] Further, since the distance measurement mode and pressure
measurement mode are switched and an ultrasonic wave is not
unnecessarily transmitted, the power consumption can be reduced. In
addition, the present embodiment has described a configuration to
switch the terminals of the circuits 442 and 443; however, the
present embodiment is not limited to this configuration and a
configuration to stop the operation of the circuits 442 and 443 may
be added. With this configuration, a compound sensor of a lower
power consumption can be realized.
[0130] Here with reference to FIG. 23, description has been given
using the configuration of a static capacitance type sensor, which
includes a membrane and opposite electrodes and described in the
third embodiment; however, the present embodiment is not limited to
this example. The present embodiment may be applied to other
configurations including the configuration described in the second
embodiment.
[0131] According to the present embodiment, since a contact
detection unit that detects a presence of a contact with a
measurement target is provided, a compound sensor having a
proximity sense and tactile sense that can accurately recognize a
contact with the measurement target can be provided.
[0132] While the present embodiment has been described with
reference to exemplary embodiments, it is to be understood that the
embodiment is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications and
equivalent structures and functions.
[0133] This application claims the benefit of Japanese Patent
Application No. 2017-162617, filed Aug. 25, 2017, which is hereby
incorporated by reference herein in its entirety.
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